Spheres can be found at all scales in both the inanimate and living world for the basic physical property of encapsulation. There has been a fair amount of work by nanotechnology researchers on putting non-biological molecules or clusters into viruses or virus-like artificial nanocontainers. Although viruses are a type of protein cage, they are not a natural part of the cell. There is a class of biological protein nanocapsules though - called vaults - that is part of cells - although their cellular functions and gating mechanism are not yet understood. Vault nanoparticles are already present in human cells in high numbers (approx. 10,000 per cell) and their hollow barrel-like structure with a large internal volume seems well suited for encapsulation purposes.
Our Spotlight today again shows an example of the very fundamental research that is taking place in labs around the world to lay the foundation for future nanotechnology based devices. It illustrates the very early stage of development and the nature of the fundamental challenges that make up today's 'nanotechnology research. The vision of revolutionary bottom-up nanotechnology is based on a concept of molecular assembly technologies where nanoscale materials and structures self-assemble to microscale structures and finally to macroscopic devices and products. Researchers are a long, long way from realizing this vision but they are busily laying the foundation for nanoscale engineering. Assembling nanoscopic components into macroscopic materials is an appealing goal but one of the enormous difficulties lies in bridging approximately six orders of magnitude that separate the nanoscale from the macroscopic world. Right now, nanotechnology researchers have their hands full just learning how to control a straight chain of nanoparticles.
Artificial skin already exists that can detect pressure and recently, thanks to carbon nanotube rubber, it now even is stretchable. Then there is stretchable artificial skin that is used, for instance, to provide grafts for human burns victims, but it is insensitive to heat and pressure. Skin-like sensitivity, or the capability to recognize tactile information, will be an essential feature of future generations of robots. Of course you could also dream up some sci-fi scenarios where artificial electronic skin vastly enhances human perception and performance. The development of electronic skin requires high-performance tactile sensors that mimic human skin in terms of touch sensation over a large area, high flexibility, resolution, and sensitivity comparable to a human finger, as well as ease of signal extraction for speed and implementation. A recent review article summarizes the current state of developing artificial touch, an area where significant progress has been made over the past few years.
Since SWCNTs are sensitive to their chemical environment, they can be intentionally doped by a variety of dopants such as iron chloride, ammonia or nitrogen dioxide. But they can also be unintentionally doped. Scientists have known for some time that something funny happens when nanotubes are sonicated in certain solvents - sometimes their electronic properties change. Since mass produced nanotubes are clumped into bundles and ropes, they need to be dispersed prior to further processing in order to separate the individual nanotubes. A popular way of doing this is by exposing the CNT samples to ultrasonic pressure waves. Adding a dispersing reagent into the solution will accelerate the dispersion effect. New research now sheds light on how and why the electronic structure of carbon nanotubes changes during sonication.
'Smart' is the key buzz word used by materials engineers when they describe the future of coatings, textiles, building structures, vehicles and just any material that you can think of. Materials are made 'smart' when they are engineered to have properties that change in a controlled manner under the influence of external stimuli such as mechanical stress, temperature, humidity, electric charge, magnetic fields etc. Smart materials have some form of sensor capability that detects a change in the material or its environment that then triggers some kind of action. Not only for use in smart materials but as general sensor materials, especially for monitoring large areas, the development of materials that act as 'chemical paints' - or coatings - by responding to a (bio)chemical parameter with a change in their optical properties has developed into an exciting new field. In a typical application, the object of interest is painted and the color or fluorescence of the paint is monitored by methods of optical imaging. This technique represents a simple but exciting new technology to monitor (bio)chemical and even physical parameters over relatively large areas and in real time without having to look at only a minute sample through a microscope.
Nanotechnology applications could provide decisive technological breakthroughs in the energy sector and have a considerable impact on creating the sustainable energy supply that is required to make the transition from fossil fuels. Possibilities range from gradual short- and medium-term improvements for a more efficient use of conventional and renewable energy sources all the way to completely new long-term approaches for energy recovery and utilization. With enough political will - and funding - nanotechnology could make essential contributions to sustainable energy supply and global climate protection policies. The technological foundation is there, all it takes is political leadership to create the right research and investment conditions to make it happen.
Radio frequency ablation (RF ablation) is a treatment for cancer that works by inserting a thin needle guided by computed tomography or ultrasound through the skin and into a tumor. Electrical energy is then delivered through a number of electrodes deployed through the needle, causing a zone of thermal destruction that encompasses the tumor. Researchers have experimented with non invasive radiowave thermal ablation of cancer cells that uses nanoparticles as a novel approach to treat cancer. The idea is that RF treatment of malignant tumors at any site in the body should be possible if it were possible to get agents that release heat under the influence of the RF field to the specific tumor site. Researchers have now developed a novel nanomaterial that has proven to be a very strong RF absorber and provides high enough thermal-ablation ability in order to generate localized thermally-driven damages inside the cancer cells. Even more, these nanoparticles have shown relatively low cytotoxicity and they absorb low frequency RF radiation, which has significant penetration depth inside living organism.
The concept of a 'machine' - a mechanical or electrical device that transmits or modifies energy to perform a certain task - can be extended to the nano-world. On the nanoscale, the nanomachine components would be atomic or molecular structures each designed to perform a specific task which, all taken together, would result in a complex function. However, these nanomachines can not be built by just further miniaturizing machine blueprints from the macro-world. Functional nanomachinery will need to take into account the quantum effects that dominate the behavior of matter at the nanoscale, affecting the optical, electrical and magnetic behavior of materials. Scientists in The Netherlands are now reporting how an atomic scale mechanical device consisting of two moving parts, each composed of only two atoms can be controlled by an external electrical signal, while being stable and providing a variety of functional modes. They jokingly refer to it as playing atomic pinball, since the two moving parts resemble the flippers in a pinball machine - unfortunately they haven't got a ball yet to play with.